Method of fluid analysis



1959 E. c. WHITEHEAD ET AL 2,899,280-

METHOD OF FLUID ANALYSIS Filed March 6, 1957 ATTORNEYS fiice Patented Aug. 11, 1959.

METHOD OF FLUID ANALYSIS Edwin C. Whitehead, Crestwood, and Andres Ferrari,

Jr., Scarsdale, N.Y., assignors to Technicon International Ltd., Chauncey, N.Y., a corporation of New York Application March 6, 1957, Serial No. 644,309

2 Claims. 01. 23-230 The present invention relates to apparatus for use in the automatic analysis of fluids.

Apparatus, of the general type to which the present invention relates, is described in the copending application of Leonard T. Skeggs, Serial No. 330,211, filed January 8, 1953, now US. Patent No. 2,797,149. As described therein, a sample liquid and one or more processing liquids are formed into a first stream which is conducted to the dialyzate compartment of a dialyzer. The undialyzed stream of liquid may be treated before it arrives at the dialyzer to facilitate the separation of the crystalloid constituents from the colloid constituents of the sample. A receiving solvent, constituted by a stream of secondary processing liquid, is conducted to the diffusate compartment of the dialyzer, the crystalloids passing through the membrane of the dialyzer into the solvent. Provision is made to introduce air into both streams before they reach the dialyzer so as to break each stream up into a plurality of liquid segments which are separated by air. The diffusate passing from the dialyzer is subjected to treatment to provide a color change in the liquid segments thereof indicative of the concentration of the factor for which the sample is being analyzed. The treated diifusate is directed to a flow cell of a colorimeter in which it is subjected to colorimetric examination to provide a quantitative indication of the factor for which the sample is being analyzed, a record being made of the colorimetric examination. Such record is in the form of a tracing or graph.

It has been found that in certain cases the record or graph of the colorimetric examination of the sample includes a spurious peak which may result in a false indication of the quantity of the factor in the sample. We have discovered that if the air, which is introduced into a continuous stream of a sample liquid in order to segment the latter, is introduced therein before a diluent or processing liquid is added to the stream, rather than after the addition of the diluent liquid thereto, such spurious peaks can be eliminated.

We believe that this result is due to the improved cleansing action of the air segments which follow the segments of sample liquid in the tubular passages of the various parts of the apparatus. In this connection, it is to be noted also that the improved cleansing action of the air is in itself a very desirable achievement because it enables the apparatus to be used for long periods of time without interruption or dismantling for cleaning purposes. Also, it is considered that by reason of the introduction of air into the stream of sampleliquid for subdividing the latter into spaced liquid segments before the diluent or other processing fluid is added to the stream of sample liquid, the proportion of sample liquid in each segment of the resulting liquid mixture is decreased with the result that the mixing of the sample liquid with the processing liquid is improved and with the additional result, especially if the sample liquid is of such character that it tends to leave a deposit on the walls of the tubular passages, that the deposit is decreased and is more easily removed from the walls by the air segments as they flow through said passages. The accomplishment of these results constitutes the principal objects and purposes of our present invention.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings, which illustrate the best modes presentlycontemplated of carrying out the invention:

Fig. 1 is a more-or-less diagrammatic view of an analyzing apparatus, pursuant to the present invention; and

Fig. 2 is a fragmentary sectional view, on an enlarged scale, of the portion of Fig. 1 which is enclosed by the broken line and which portion is designated by the arrow head 2.

Referring now to the drawings in detail, the automatic analyzing apparatus 10 includes an automatic analyzing means, generally indicated by the reference numeral 12, to which liquid samples, such as for example and not by Way of limitation, body fluid samples, industrial samples, or the like, which are to be analyzed, are fed; a colorimeter 14 for effecting a colorimetric examination of the output of the analyzer means 12, and a recording means 16 for recording the colorimetric examination of the output of said analyzer means 12.

The analyzer means 12 includes a dialyzer 18 to which the liquid samples being analyzed and various liquids processing media are fed'thereto in predetermined proportions. More specifically, a proportioning pump 20 is utilized to feed a liquid sample, one or more primary processing media, depending upon the sample being tested, and air through the lines 22, 24 and 26, respectively, into the conduit or line 28. Pursuant to the present invention, the air is introduced into the continuous stream of sample liquid in the conduit 28 before the diluent or processing liquid is introduced into the sample liquid stream in the conduit. As shown herein, a plurality of moving rollers 54 compress the flexible tubes 22, 24, 26, 30, 32 and 34 at spaced points therealong, against an underlying bed or platen 56, to advance the material to be pumped therethrough. Proportioning pumps, of the type suitable for use herein, are illustrated and described in the copending applications of Jack Isreeli and Andres Ferrari, Serial No. 628,030, filed December 13, 1956, and Serial No. 463,860, filed October '22, 1954, both of which are assigned to the assignee herein, and also in the previously identified Skeggs application. The samples may be introduced to the pump 20, and specifically to the line or conduit 22 thereof, from a suitable flask or flasks, as illustrated and described in said Skeggs application, or provision may be made for a suitable automatic sample feed device. An automatic sample feed device 36, suitable for the purpose herein, is illustrated and described in the copending application of Leonard T. Skeggs, Serial No. 547,087, filed November 16, 1955. As here shown, said feed device comprises a turntable or plate 38 provided with the recesses or receptacles 40 forthe sample liquids. Said plate is mounted for rotation, as indicated by the arrow 42, relative to a suction intake device 37 through which the samples flow into the conduit 22, as indicated by the arrow 39, for a quantitative analysis by the apparatus 10 of a predetermined factor or separable substance in the sample. The recorder 16 of the apparatus provides a trace or graph recording 44 of said quantitative analysis. The maximum concentrations or indications on the graph is indicated by the trace portions 46.

Heretofore, spurious peaks were sometimes recorded at said maximum trace portions 46, said peaks providing misleading results. However, pursuant to the present invention, the possibility of recording such spurious peaks has been eliminated. In accordance with the present invention, the sample liquid S is pumped through the conduit 22 into conduit 28 and air is pumped through the conduit 26 and introduced into the conduit 28 before a diluent or processing liquid is introduced into conduit 28. As best shown in Fig. 2, conduits 22 and 26 feed into conduit 28 so that the air breaks up the sample liquid S into the liquid segments L thereof which are separated by air segments A. The pump operates also to pump a diluent liquid or primary processing medium D through the conduit 24, which has a junction at 52 with conduit 28, to add the diluent liquid to the sample segments L, as indicated by the segment CS.

More specifically, the pump conduits 22 and 26, for the sample and the air, respectively, are each connected into the conduit 28 at the input end 48 of the latter. The air supplied by the conduit 26 breaks up the sample S, supplied by the tube 22, into segments of liquid L, which segments are separated by air segments or bubbles, as indicated at A. The direction of liquid flow through the conduit 28 is indicated by the arrow 50. The tube 24, through which the primary processing medium or diluent liquid D is pumped, is connected into the conduit 28 at said junction 52, the latter being beyond or after the input end 48 of the conduit 28, considered in the direction 50 of the liquid flow in the conduit 28.

It will be noted that the segment CS comprises a portion S, of the sample liquid, which portion was constituted by a prior segment L, and a portion of the diluent material D, the combined segment CS having a greater volume than the segment L and being spaced therefrom by an air bubble or segment A. It will be understood that the combined segments CS are spaced from each other by air segments or bubbles A as they move along the conduit 28 in the direction of the arrow 50. The pump 20 also operates to provide in the conduit 54 to the other side of the dialyzer 18 segments, similar to L, of secondary processing fluid, the secondary processing fluid being pumped through the tube 30 and the air being pumped through the tube 34, said tubes having a junction as at 56 at the input to the conduit 54.

The segments CS containing both the sample fluid S and the diluent fluid D, pass along the conduit 28 to a mixer 58. The mixer 58, as here shown, is preferably of the type illustrated and described in the copending application of Andres Ferrari, Serial No. 609,366, filed September 12, 1956, and assigned to the assignee hereof. As therein described, the mixing device 58 is constituted by a helical coil or tubing in which the segments CS are thoroughly mixed as they flow through the convolutions 60 of the helical mixing device. From the mixer 58, the liquid segments CS flow through a conduit 62, as indicated by arrows 63, to the dialyzate compartment 64 of the dialyzer 18. In the dialyzer, a separable constituent, related to the factor for which the analysis is being made, is removed from the flowing stream constituted by the segments CS. For example, and not by way of limitation, in the analysis of a body fluid, such as blood, the crystalloid constituents and the colloid constituents of the body fluid sample are separated, the crystalloids passing through the dialyzer membrane 66 into the diffusate compartment 68. The mixture, from which thec rystalloids have been dialyzed, pass out of the dialyzer through the conduit 70.

As previously indicated, the pump 20 also feeds into line 54, through the tubes 30 and 32, a secondary processing medium and air, respectively, the pump being operative to break the secondary processing medium into air separated segments which form the receiving solvent. The receiving solvent, for the particular sample being analyzed, is fed through the line 54, as indicated by the arrow 72, to the diffusate compartment 68 of the dialyzer from whence it passes into the conduit 74. In the dialyzer, the separable substance, for example the crystalloid constituent, in the case of blood, in the segments of the un- 4 dialyzed liquid pass into the segments of the receiving solvent.

The receiving solvent, which is sent to the dialyzer compartment 68 by way of line 54, passes, as a dilfusate into the conduit 74. Simultaneously, the required reagent is pumped through the tube 34 into the conduit 76, and through the latter, as indicated by the arrow 78, into the conduit 74. The mixture of the ditfusate and the reagent then passes into a mixer coil 58. From the mixer coil 58, the mixture passes through the coil 80, of a heating bath 82, passing out of the bath into a conduit 84 which directs the mixture into a blending device 86.

Assuming now, by way of example, and not by way of limitation, that the sample under analysis is a body fluid which is being analyzed for glucose, the primary processing fluid or diluent introduced through the pump tube 24 may be constituted by a mixture of sodium chloride and caprylic alcohol, the secondary processing medium introduced through the pump tube 30 may be constituted by a solution of potassium ferricyanide, and the reagent introduced through the pump tube 34 may be constituted by a mixture of sodium chloride and potassium cyanide. In the upper half of the dialyzer, the glucose, which is a soluble crystalloid, diffuses through the membrane 66 in proportion to its concentration in the mixture that is being fed to the dialyzer through the conduit 62. Simultaneously, the lower half 68 of the dialyzer is supplied with the continuous stream of the potassium ferricyanide solution, in air spaced segments thereof. In the dialyzer, the potassium fem'cyanide solution picks up the glucose that diffuses through the membrane 66 and, after mixture with the reagent, passes into the coil of the heater 82. In traveling through the coil 80, the mixture undergoes a chemical change, any glucose acting to reduce the potassium ferricyanide to potassium ferrocyanide, the sensitivity of the reaction being increased by the mixture of the sodium chloride and potassium cyanide.

Potassium ferricyanide in solution in unreduced form is yellow in color; after its reduction to the ferrocyanide, its solution is colorless. If, therefore, glucose is present in the test sample being analyzed, there will be a proportionate reduction of the potassium ferricyanide in coil 80, with an accompanying loss of color. Consequently, the bath 82 serves to develop in the mixture a degree of color, different from that of a solution of unreduced potassium ferricyanide, on the basis of which it is possible to make a photometric examination in the colorimeter 14 and to record said examination in the recorder 16. However, since the mixture flowing out of the mixer 58 is in the form of air spaced segments of liquid, it is desirable to eflect a blending of the segments 'of the diffusate, before they pass into the colori1neter 14, so as to provide a gradual transition or progression of color change, as distinct from the series of individual color changes, so as to produce a colorimeter recording which is smooth and regular in appearance. Therefore, the liquid segments are directed from the conduit 84 into the blender 86 which blends the segments of the diflusate together and which also releases the air from the fluid flowing out of the heater coil. A blender 86, suitable for the purpose herein, is described in each of the copending applications of Edwin C. Whitehead and Andres Ferrari, Jr., Serial No. 573,539, filed March 29, 1956, now abandoned, and Serial No. 607,- 122, filed August 30, 1956 and both assigned to the assignee hereof.

The colorimeter 14 may be of any suitable type. The blended fluid flows from the blender 86 into the colorimeter 14, said colorimeter controlling the operation of the recorder 14, as described in the above-mentioned Skeggs applications.

The trace produced by the recorder is indicated at 44 and clearly indicates the maximum concentration points at 46 of the factor, for example glucose, for

aseaaso which the analysis is being made. It will be noted that said maximum concentration points are smoothly rounded oil? so that they may be readily determined on the recording and understood. The trace 44 is completely free of the spurious or undesirable peaks which formerly occurred and which resulted in improper readings or false interpretations of the trace.

Consequently, it will be apparent, that due to the basic inventive concept of the present invention, pursuant to which the diluent or primary processing material is introduced into or mixed with the sample after the latter is segmented by the introduction of air therein, said undesirable peaks'are eliminated, and a correct and true trace or recording is provided by the recorder 16.

While the present invention has been illustrated and described in connection with the analysis of a body fluid for glucose, it will be readily apparent that it is not limited thereto. More specifically, and not by way of limitation, body fluids may be analyzed for other factors, utilizing the basic concept of the present invention, such as, for example and not by way of limitation, urea, nitrogen, calcium, etc. In addition, it will also be understood that the present invention is not limited to the analysis of body fluids but that other liquids which contain a substance or factor which can be diffused or separated therefrom, may be analyzed pursuant to the present invention to provide a quantitative recording of said substance or factor, which recording is free of spurious peaks.

While we have shown and described the preferred embodiments of our invention, it will be understood that various changes may be made in the idea or principles of the invention within the scope of the appended claims.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. In a method of obtaining a quantitative indication of a substance in a liquid according to which said liquid and a processing liquid and air are transmitted in the form of a flowing stream in a conduit and according to which said air is eflective to divide said stream into a series of spaced liquid segments separated from each other by intervening segments of air, comprising introducing said air into said conduit at a time not later than the introduction of said processing liquid whereby the formation of said liquid segments occurs not later than the introduction of said processing liquid.

2. In a method-of obtaining a quantitative indication of a substance in a liquid according to which said liquid and a processing liquid and air are transmitted in the form of a flowing stream in a conduit and according to which said air is effective to divide said stream into a series of spaced liquid segments separated from each other by intervening segments of air, comprising introducing said air into said conduit at a time not later than the introduction of said processing liquid whereby the formation of said liquid segments occurs not later than the introduction of said processing liquid, and transmitting the segmented stream through a mixer for intermixing the liquids of said segmented stream with each other.

References Cited in the file of this patent UNITED STATES PATENTS 2,797,149 Skeggs June 25, 1957 

1. IN A METHOD OF OBTAINING A QUANTITATIVE INDICATION OF A SUBSTANCE IN A LIQUID ACCORDING TO WHICH SAID LIQUID AND A PROCESSING LIQUID AND AIR ARE TRANSMITTED IN THE FORM OF A FLOWING STREAM IN A CONDUIT AND ACCORDING TO WHICH SAID AIR IS EFFECTIVE TO DIVIDE SAID STREAM INTO A SERIES OF SPACED LIQUID SEGMENTS SEPARATED FROM EACH OTHER BY INTERVENING SEGMENTS OF AIR, COMPRISING INTRODUCING SAID AIR INTO SAID CONDUIT AT A TIME NOT 